Hybrid anti-rust pigment based on attapulgite modification and application of hybrid anti-rust pigment in anticorrosive paint

Abstract

The invention relates to a hybrid anti-rust pigment based on attapulgite modification and application of the hybrid anti-rust pigment in an anti-corrosion coating. The natural nano material attapulgite has the characteristics of high specific surface area, surface activity, high porosity, good chemical stability and the like. The characteristics endow the attapulgite with the capability and special behaviors of serving as a carrier. According to the invention, attapulgite is taken as a carrier, and an organic acid corrosion inhibitor is successfully loaded on attapulgite after purification with inorganic acid and modification with inorganic salt, so that a novel hybrid anti-rust pigment is obtained. The characteristic that the organic acid corrosion inhibitor can react with Fe < 3 + > to generate a complex is utilized, so that the corrosion inhibition function of the carbon steel is realized. And carrying out vacuum drying on the loaded product to obtain an anti-rust pigment product. The novel hybrid anti-rust pigment has the shielding effect of the attapulgite and the complexing anti-rust effect of the organic acid corrosion inhibitor. The hybrid anti-rust pigment is added into an epoxy matrix according to the proportion of 1 wt.%-10 wt.%, and the corrosion protection effect on carbon steel can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-rust pigments and anti-corrosion coatings, and in particular to a hybrid anti-rust pigment based on modified attapulgite and application thereof in anti-corrosion coatings. Background Art

[0002] Carbon steel is widely used in shipbuilding, construction, and other areas due to its excellent performance. However, it is inherently highly corrosion-sensitive and will corrode rapidly during service. Organic coatings are often used to protect carbon steel, providing effective barrier protection and corrosion resistance, thereby extending the service life of carbon steel. However, organic coatings often have limited protective capabilities for carbon steel due to microcracks generated during the preparation process and a lack of effective anti-corrosion pigments, resulting in significant economic losses in subsequent maintenance. Therefore, it is crucial to add fillers and anti-rust pigments to organic coatings to achieve long-term corrosion protection and protection for carbon steel substrates.

[0003] Therefore, the existing technology still needs to be improved and enhanced. Summary of the Invention

[0004] In view of the shortcomings of the above-mentioned prior art, the present invention aims to provide a hybrid anti-rust pigment modified with attapulgite and its application in anti-corrosion coatings, thereby achieving both the "shielding" and "corrosion inhibition" functions of the hybrid anti-rust pigment in the coating. The problems to be solved are the dispersibility of attapulgite and the improvement of the loading capacity of attapulgite as a carrier.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, a hybrid anti-rust pigment based on modified attapulgite is provided. The pigment is attapulgite modified by chemical inorganic acid activation treatment, and the pigment comprises 5 to 15 parts of attapulgite, 300 to 700 parts of inorganic acid, 2 to 4 parts of inorganic salt, and 4 to 6 parts of organic acid corrosion inhibitor in parts by weight.

[0006] In a second aspect, a method for preparing a hybrid anti-rust pigment based on attapulgite modification comprises the following steps: (1) Activating attapulgite with an inorganic acid to prepare an attapulgite suspension, and centrifuging the suspension to remove the insoluble matter to obtain product 1; (2) dissolving the inorganic salt in deionized water, mixing with the product 1, centrifuging to obtain the insoluble matter and vacuum drying to obtain the product 2; (3) The organic acid corrosion inhibitor was dissolved in anhydrous ethanol and then mixed with the second product. The mixture was stirred at a constant temperature for 30 min and then vacuum adsorbed for 2 h. The constant temperature stirring and vacuum adsorption steps were repeated 3 times. The organic acid corrosion inhibitor was loaded into the pore structure of the attapulgite by pressurization, washed with ethanol, and vacuum dried to obtain a hybrid anti-rust pigment.

[0007] Furthermore, the raw material used in the chemical inorganic acid activation method is one of sulfuric acid, hydrochloric acid, and nitric acid; the inorganic salt is one of ammonium fluoride and ammonium chloride; and the organic acid corrosion inhibitor is one of tannic acid, gallic acid, and phytic acid.

[0008] Furthermore, in step (1), the mass ratio of attapulgite to inorganic acid is 5-15:300-700, and after ultrasonic dispersion for 30 minutes, the attapulgite suspension is prepared by high-speed stirring at a constant temperature of 70°C for 6 hours.

[0009] Furthermore, in step (2), the mass ratio of inorganic salt to deionized water is 2-4:340-670, the temperature of constant temperature stirring and dispersion is 15-25°C, and the time is 4-8 h.

[0010] Furthermore, in step (3), the mass ratio of the organic acid corrosion inhibitor to anhydrous ethanol is 4-6:50-100, the constant temperature stirring temperature is 20-25°C, the vacuum drying temperature is 50-70°C, and the drying time is 10-14 h.

[0011] The present invention purifies attapulgite using an inorganic acid, then modifies the attapulgite using an inorganic salt to improve the attapulgite's loading capacity. Finally, an organic acid corrosion inhibitor is loaded into the pore structure of the attapulgite by vacuum adsorption to prepare a hybrid anti-rust pigment. The hybrid anti-rust pigment is added to an epoxy coating matrix to form an epoxy coating containing the hybrid anti-rust pigment based on the modified attapulgite.

[0012] In a third aspect, a hybrid anti-rust pigment is used in an anti-corrosion coating. The anti-corrosion coating includes component A and component B. Component A is prepared by the following components and mass ratios, calculated by weight: 40 to 60 parts of solvent-based bisphenol A epoxy resin (NPSN-901-75X), 20 to 30 parts of solvent xylene, 0.4 to 0.6 parts of dispersant (BYK 110), 0.4 to 0.6 parts of wetting agent (BYK 306), 0.6 to 1.0 parts of defoaming agent (BYK 065), and 1 to 10 parts of hybrid anti-rust pigment; component B includes 20 to 40 parts of 650# polyamide curing agent.

[0013] Furthermore, 1 wt.% to 10 wt.% of chemically acid-activated and loaded-modified attapulgite was added to component A of the anti-corrosion coating, dispersed in a high-speed disperser for 30 min, and ground in a ball mill for 4 to 12 h to obtain component A of the anti-corrosion coating containing a hybrid anti-rust pigment based on chemically acid-activated and loaded-modified attapulgite. Component A and component B (curing agent) were mixed and applied on the surface of carbon steel to form an anti-corrosion coating.

[0014] The present invention makes full use of the pore structure of attapulgite, and increases the pore structure of attapulgite through inorganic acid purification and inorganic salt modification. Finally, the organic acid corrosion inhibitor is "pressed" into the pore structure of attapulgite by pressurization, thereby realizing the combination of "attapulgite-organic acid". On the one hand, the impurities and a large amount of bound water in the attapulgite are removed by inorganic acid purification. On the other hand, the pore structure of the attapulgite is increased by inorganic salt modification to load more organic acid corrosion inhibitor. The former can remove impurities and expose the pore structure of the attapulgite itself, while the latter can increase the pore structure of the attapulgite to load more organic acid corrosion inhibitor, ultimately allowing this hybrid anti-rust pigment to exert its corrosion inhibition ability in the coating.

[0015] The advantages and beneficial effects of the present invention are as follows: 1. Attapulgite, a rod-shaped nanofiller, has a certain barrier effect. This invention uses an inorganic acid as a solvent to purify the attapulgite, then modifies it with an inorganic salt to enhance its load-bearing capacity. Finally, an organic acid corrosion inhibitor is pressurized into the pore structure of the attapulgite, thereby obtaining a new hybrid anti-rust pigment.

[0016] 2. Utilizing the stimulus-responsive release of organic corrosion inhibitors under acidic conditions, the local acidic environment generated when corrosion occurs stimulates the organic corrosion inhibitor to separate from the carrier, exerting its corrosion inhibition effect. This new hybrid anti-rust pigment not only possesses the shielding effect of attapulgite itself, but also possesses the corrosion inhibition and rust prevention effects of organic acid corrosion inhibitors.

[0017] 3. The hybrid anti-rust pigment of the present invention can be added to epoxy-based coatings at a ratio of 1 to 10 wt.% by releasing an organic acid corrosion inhibitor effective for carbon steel substrates. This coating can be used for corrosion protection of carbon steel substrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 :(a1), (a2), (a3) are the macromorphology, micro SEM morphology and cross-sectional morphology of Q235 carbon steel after immersion in a 0.01 M NaCl aqueous solution for 36 h; (b1), (b2), (b3) are the macromorphology, micro SEM morphology and cross-sectional morphology of Q235 carbon steel after immersion in a leachate formed by adding a 0.01 M NaCl aqueous solution to modified and loaded attapulgite with organic acid corrosion inhibitor for 36 h; Figure 2:(a-c) are the electrochemical impedance spectra of the epoxy coating on the surface of Q235 carbon steel immersed in 3.5 wt.% NaCl aqueous solution, including: (a) epoxy varnish; (b) epoxy varnish + attapulgite; (c) epoxy varnish + organic acid corrosion inhibitor modified attapulgite; In Figures (a-c), the horizontal axis Frequency represents the frequency (Hz), and the vertical axis |Z| on the left represents the impedance modulus (Ω·cm 2 ), the right vertical axis Phase Angle represents the phase angle (Deg.); (d) is the |Z| of the three coatings 0.01 Hz value; Figure 3 : R of Comparative Example 1 (epoxy varnish), Comparative Example 2 (epoxy varnish + attapulgite) and Example (epoxy varnish + organic acid corrosion inhibitor modified attapulgite) after electrochemical impedance spectroscopy fitting ct Value. Among them, the horizontal axis Time represents the test time (day), and the vertical axis represents |Z| 0.01 Hz (low frequency impedance value) (Ω·cm 2 ); Figure 4 Macromorphology of epoxy coatings on Q235 carbon steel surface after 360 h of salt spray test: (a) epoxy varnish; (b) epoxy varnish + attapulgite; (c) epoxy varnish + attapulgite modified with organic acid corrosion inhibitor. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] Attapulgite is a naturally occurring nanomaterial that is abundant and inexpensive. Its high aspect ratio, high specific surface area, one-dimensional nanorod morphology, regularly arranged pore structure, abundant active sites, and excellent chemical stability give it excellent load-bearing capacity. In addition to its high load-bearing capacity, attapulgite also exhibits excellent high-temperature resistance and acid and alkali resistance. Attapulgite can be used as a functional additive and filler in coatings. Its good miscibility with epoxy resins improves the mechanical properties of epoxy composites. However, when attapulgite is directly added to polymer materials, the composite material significantly reduces its effective surface area due to the large number of voids between the filler and the polymer, leading to significant deterioration in mechanical properties. Furthermore, as mentioned above, as a nanomaterial, when it is processed into an ultrafine powder, the increased specific surface area and surface energy make the particles unstable and prone to agglomeration. This agglomeration can lead to a decrease in the mechanical properties and corrosion resistance of the coating. Among non-polar organic compounds, attapulgite also has poor dispersibility. Therefore, the dispersion problem of attapulgite in coating applications must be addressed. High-speed shear dispersion can be used to uniformly mix it with the coating. For example, existing techniques have employed ultrasonic and electric stirring for 2 hours to obtain a uniformly dispersed single rod-shaped crystal system, as observed under a transmission electron microscope. Alternatively, pigments have been prepared using both stirring and ball milling methods. Scanning electron microscopy results indicate that ball milling can achieve a more uniform dispersion of attapulgite.

[0021] The unique pore structure of attapulgite provides it with excellent load-bearing capacity. For example, a bifunctional nanocomposite composed of 2-mercaptobenzothiazole-coated graphene oxide has been developed and embedded in attapulgite. Application to epoxy coatings has shown that the addition of this pigment improves the coating's mechanical properties and enhances its permeability. Even after 50 days of immersion, the coating maintained an impedance of 8.13 GΩ·cm. 2 In the prior art, BTA@ATP was prepared by modifying attapulgite with benzotriazole (BTA), and a smart water-based epoxy coating was developed for self-repair of epoxy coatings. EIS test results showed that after immersion for 15 days, the epoxy coating containing nanocontainers loaded with corrosion inhibitors had a |Z| 0.01 HzThe value increased by an order of magnitude compared to pure epoxy resin coatings, significantly improving the corrosion resistance of the epoxy matrix. Using attapulgite as a carrier, silver nanoparticles (AgNPs) were deposited on the attapulgite surface via a one-pot in situ polymerization method and then coated with polyaniline (PANI) to produce an ATP / PANI / AgNPs nanocomposite, which was then applied to epoxy coatings. The results showed that the composite surface was rough, retained the attapulgite structure, and exhibited a more uniform dispersion. Compared to a blank coating, the low-frequency impedance of the ATP / PANI / AgNPs composite coating was an order of magnitude higher after immersion in 0.5 M NaCl solution for 192 h. The epoxy coating containing 2 wt.% of the ATP / PANI / AgNPs nanocomposite exhibited superior corrosion resistance and corrosion protection, suggesting broad application prospects in the marine industry. Prior art methods include modifying attapulgite with a silane coupling agent and loading the modified attapulgite with the organic corrosion inhibitor 2-mercaptobenzothiazole. Research has shown that at pH 3, the organic corrosion inhibitor 2-mercaptobenzothiazole is rapidly released from the carrier attapulgite, reaching a maximum release rate of 95.9% after 144 hours. Electrochemical impedance spectroscopy and salt spray tests have shown that the addition of pigments enhances the shielding and corrosion resistance of polyurethane coatings. The release of the organic corrosion inhibitor can provide a dense protective film on the metal substrate, inhibiting corrosion reactions.

[0022] In the first aspect, a hybrid anti-rust pigment based on modified attapulgite is provided. The pigment is attapulgite modified by chemical inorganic acid activation treatment. The pigment comprises, by weight, about 5 to 15 parts of attapulgite, about 300 to 700 parts of inorganic acid, 2 to 4 parts of inorganic salt, and about 4 to 6 parts of organic acid corrosion inhibitor.

[0023] In a second aspect, a method for preparing a hybrid anti-rust pigment based on attapulgite modification comprises the following steps: (1) Activating attapulgite with an inorganic acid to prepare an attapulgite suspension, and centrifuging the suspension to remove the insoluble matter to obtain product 1; (2) dissolving the inorganic salt in deionized water, mixing with component 1, centrifuging to obtain the insoluble matter and vacuum drying to obtain product 2; (3) The organic acid corrosion inhibitor was dissolved in anhydrous ethanol and then mixed with component 2. The mixture was stirred at a constant temperature for 30 minutes and then vacuum adsorbed for 2 hours. The "constant temperature stirring-vacuum adsorption" step was repeated 3 times. The organic acid corrosion inhibitor was loaded into the pore structure of the attapulgite by pressurization. The mixture was washed with ethanol and vacuum dried to obtain product 3, i.e., attapulgite modified with an organic acid corrosion inhibitor, which is also the hybrid anti-rust pigment of the present invention.

[0024] Furthermore, the raw material used in the chemical inorganic acid activation method is one of sulfuric acid, hydrochloric acid, and nitric acid; the inorganic salt is one of ammonium fluoride and ammonium chloride; and the organic acid corrosion inhibitor is one of tannic acid, gallic acid, and phytic acid.

[0025] Furthermore, in step (2), the temperature of the constant temperature stirring dispersion is 15-25°C and the time is 4-8 h.

[0026] Furthermore, in step (3), the constant temperature stirring temperature is 20-25°C, the vacuum drying temperature is 50-70°C, and the drying time is 10-14 h.

[0027] In a third aspect, a hybrid anti-rust pigment is used in an anti-corrosion coating. Component A is prepared by the following components and mass ratios, calculated by weight: 40 to 60 parts of solvent-based bisphenol A epoxy resin (NPSN-901-75X), 20 to 30 parts of solvent xylene, 0.4 to 0.6 parts of dispersant (BYK 110), 0.4 to 0.6 parts of wetting agent (BYK 306), 0.6 to 1.0 parts of defoaming agent (BYK 065), and 1 to 10 parts of hybrid anti-rust pigment; component B is 20 to 40 parts of 650# polyamide curing agent.

[0028] In the preparation of the anti-corrosion coating: 1 wt.%~10 wt.% of chemically acid-activated and loaded-modified attapulgite is added to the anti-corrosion coating component A, dispersed in a high-speed disperser for 30 minutes, and ground in a ball mill for 4~12 hours to obtain the anti-corrosion coating component A of a hybrid anti-rust pigment based on chemically acid-activated and loaded-modified attapulgite. Component A and component B (curing agent) are mixed and applied to the carbon steel surface to form an anti-corrosion coating.

[0029] The present invention makes full use of the pore structure of attapulgite, and increases the pore structure of attapulgite through inorganic acid purification and inorganic salt modification. Finally, the organic acid corrosion inhibitor is "pressed" into the pore structure of attapulgite by pressurization, thereby realizing the combination of "attapulgite-organic acid". On the one hand, the impurities and a large amount of bound water in the attapulgite are removed by inorganic acid purification. On the other hand, the pore structure of the attapulgite is increased by inorganic salt modification to load more organic acid corrosion inhibitor. The former can remove impurities and expose the pore structure of the attapulgite itself, while the latter can increase the pore structure of the attapulgite to load more organic acid corrosion inhibitor, ultimately allowing this hybrid anti-rust pigment to exert its corrosion inhibition ability in the coating.

[0030] The present invention further illustrates the properties of the hybrid anti-rust pigment based on attapulgite modification through the following examples: Example 1 In this embodiment, the preparation method of the hybrid anti-rust pigment and anti-corrosion coating based on attapulgite modification is as follows: (1) 10 g of attapulgite was dissolved in 500 ml of dilute hydrochloric acid and ultrasonically dispersed for 30 min. The mixture was then stirred at 1200 rpm min at a constant temperature of 70 °C. -1 The mixture was stirred at 500 rpm for 6 h, centrifuged, and the insoluble matter was dried under vacuum to obtain product 1. 3 g of ammonium fluoride pellets were dissolved in deionized water, and product 1 was added and mixed thoroughly. The mixture was stirred at 25°C for 6 h. The mixture was washed three times with deionized water and then with anhydrous ethanol, then centrifuged at high speed and dried under vacuum at 60°C for 12 h to obtain product 2.

[0031] (2) Product 2 was dissolved in 50 ml of anhydrous ethanol, and 5 g of tannic acid, an organic corrosion inhibitor, was added. The mixture was stirred at a constant temperature for 30 min and then vacuum-adsorbed for 2 h. During the vacuum-adsorption process, the vacuum degree must reach -0.1 MPa (gauge pressure) and must be maintained at this level during the vacuum-adsorption stage. The "constant temperature stirring-vacuum-adsorption" step was repeated three times. The product was washed with ethanol three times and dried to obtain a modified attapulgite loaded with tannic acid, i.e., Product 3, which is also the hybrid anti-rust pigment of the present invention.

[0032] (3) The formula of the hybrid anti-rust pigment based on attapulgite modified in epoxy coating is as follows: Component A: 50 parts of bisphenol A epoxy resin (NPSN-901-75X), 6 parts of hybrid anti-rust pigment, 0.5 parts of dispersant (BYK 110), 0.5 parts of wetting agent (BYK 306), 1.0 parts of defoaming agent (BYK 065). -1 The mixture was dispersed at high speed for 30 min, and then ground in a ball mill at 300 rpm for 6 h; Component B: 30 parts of 650# polyamide curing agent and 25 parts of solvent xylene.

[0033] Components A and B were mixed to produce an anticorrosive coating containing an antirust pigment based on an inorganic acid, ammonium fluoride, and organic acid-modified attapulgite. The coating was sprayed onto sandblasted Q235 carbon steel (150 mm × 70 mm × 2 mm for salt spray testing and 50 mm × 50 mm × 2 mm for electrochemical impedance spectroscopy testing) and cured at room temperature for 72 hours. The dry film thickness of the coating was 67 ± 3 μm.

[0034] Comparative Example In this comparative example, the solvent-based epoxy coating varnish formulation of Example 1 without the hybrid anti-rust pigment (referred to as Comparative Example 1) and the solvent-based epoxy coating varnish formulation in which the hybrid anti-rust pigment was replaced with attapulgite (referred to as Comparative Example 2) were used. Both coatings were evenly sprayed onto the surface of a carbon steel structure and cured at room temperature for 72 hours, resulting in a dry film thickness of 67±3 μm.

[0035] By the attached Figure 1 As can be seen from a1, a2, and a3 in the figure, a large amount of yellow corrosion products and black corrosion products (a1) were generated on the carbon steel surface after being immersed in 0.01 M NaCl solution without hybrid anti-rust pigment precipitate for 36 h, indicating that the corrosion products of carbon steel are mainly iron oxides. At this time, the microscopic morphology of the substrate surface can hardly see the smooth surface of the original substrate, but is covered by loose and porous corrosion products (a2). A large corrosion pit can also be seen in the cross-sectional morphology (a3). Figure 1 As shown in Figures b1, b2, and b3, a blue protective film (b1) forms on the carbon steel surface after immersion for 36 hours in a 0.01 M NaCl solution containing the hybrid anti-rust pigment precipitate. Electron microscopic images of the substrate surface reveal only scattered corrosion products (b2), while the cross-sectional morphology reveals shallow, less pronounced corrosion pits (b3). This suggests that the addition of the hybrid anti-rust pigment can slow the corrosion rate of the carbon steel substrate.

[0036] Attachment Figure 2 The following are the electrochemical impedance spectroscopy test results of the scratch coating of (a) epoxy varnish; (b) epoxy varnish + attapulgite; (c) epoxy varnish + organic acid corrosion inhibitor modified attapulgite; (d) |Z| of Comparative Examples 1 and 2 and Example 1 on different days. 0.01 Hz It can be seen that the low-frequency impedance values of the two comparative example coatings (a) and (b) continue to decrease with the increase of the test time, while the low-frequency impedance value of the embodiment coating shown in Figure c rebounds on the 10th day and then decreases again. In addition, during the test, the low-frequency impedance value of the embodiment coating |Z| 0.01 Hz The values are greater than those of the comparative example, indicating that the coating of the embodiment has better corrosion resistance. This is because the release of the organic acid corrosion inhibitor plays a corrosion inhibition role, which in turn causes |Z| 0.01 Hz The rise of value.

[0037] Attachment Figure 3 Shown are R of Comparative Examples and Examples ct Value comparison chart. R ct It is an important indicator for evaluating the corrosion resistance of coatings. The larger the value, the stronger the corrosion resistance of the coating. Figure 3 It can be seen that the R ct The values are significantly higher than those of the epoxy varnish coating (Comparative Example 1) and the epoxy varnish coating containing attapulgite (Comparative Example 2), indicating that the addition of hybrid anti-rust pigments can enhance the corrosion inhibition ability of the epoxy varnish coating on the Q235 carbon steel substrate.

[0038] Attachment Figure 4The macromorphology of (a) epoxy varnish; (b) epoxy varnish + attapulgite; (c) epoxy varnish + organic acid corrosion inhibitor modified attapulgite after 360 hours of salt spray test. As can be seen from Figure a, after 360 hours of salt spray test, the epoxy varnish coating has a lot of rust on the scratches. The corrosive medium diffuses into the coating from the scratches, causing the coating to peel off from the scratches to both sides, and the peeling distance almost reaches the edge of the substrate. The degree of corrosion of the coating shown in Figure b is lighter than that of the coating shown in Figure a. This is due to the shielding properties of the attapulgite itself. The peeling distance of the coating to both sides is about 6 mm - 8 mm. The coating of the embodiment shown in Figure c has the lightest degree of corrosion. This is due to the organic acid corrosion inhibitor and the corrosion product Fe 3+ The complex produced by the complexation action adheres to the scratch and forms a protective film, which can hinder the diffusion of the corrosive medium to the surface of the substrate, thereby achieving corrosion inhibition.

[0039] Example 2 In this embodiment, the preparation method of the hybrid anti-rust pigment and anti-corrosion coating based on attapulgite modification is as follows: (1) 5 g of attapulgite was dissolved in 300 ml of dilute hydrochloric acid and ultrasonically dispersed for 30 min. The mixture was then stirred at 1000 rpm min at a constant temperature of 70 °C. -1 The mixture was stirred at 400°C for 6 hours, centrifuged, and the insoluble matter was dried under vacuum to obtain product 1. 2 g of ammonium fluoride granules were dissolved in deionized water, and product 1 was added and mixed thoroughly. The mixture was stirred at 25°C for 6 hours. The mixture was washed three times with deionized water and then with anhydrous ethanol, then centrifuged at high speed and dried under vacuum at 60°C for 12 hours to obtain product 2.

[0040] (2) Product 2 was dissolved in 50 ml of anhydrous ethanol, and 4 g of tannic acid, an organic corrosion inhibitor, was added. The mixture was stirred at a constant temperature for 30 min and then vacuum-adsorbed for 2 h. During the vacuum-adsorption process, the vacuum degree must reach -0.1 MPa (gauge pressure) and must be maintained at this level during the vacuum-adsorption stage. The "constant temperature stirring-vacuum-adsorption" step was repeated three times. The product was washed with ethanol three times and dried to obtain a modified attapulgite loaded with tannic acid, i.e., Product 3, which is also the hybrid anti-rust pigment of the present invention.

[0041] (3) The formula of the hybrid anti-rust pigment based on attapulgite modified in epoxy coating is as follows: Component A: 40 parts of bisphenol A epoxy resin (NPSN-901-75X), 2 parts of hybrid anti-rust pigment, 0.6 parts of dispersant (BYK 110), 0.4 parts of wetting agent (BYK 306), and 0.8 parts of defoaming agent (BYK 065). -1The mixture was dispersed at a high speed of 30 min, and then ground using a ball mill at a speed of 300 rpm for 6 h; component B: 24 parts of 650# polyamide curing agent and 20 parts of solvent xylene.

[0042] Components A and B were mixed to produce an anticorrosive coating containing an antirust pigment based on an inorganic acid, ammonium fluoride, and organic acid-modified attapulgite. The coating was sprayed onto sandblasted Q235 carbon steel (150 mm × 70 mm × 2 mm for salt spray testing and 50 mm × 50 mm × 2 mm for electrochemical impedance spectroscopy testing) and cured at room temperature for 72 hours. The dry film thickness of the coating was 67 ± 3 μm.

[0043] Example 3 In this embodiment, the preparation method of the hybrid anti-rust pigment and anti-corrosion coating based on attapulgite modification is as follows: (1) 15 g of attapulgite was dissolved in 700 ml of dilute hydrochloric acid and ultrasonically dispersed for 30 min. The mixture was then stirred at 1400 rpm min at a constant temperature of 70 °C. -1 The mixture was stirred at 400°C for 6 hours, centrifuged, and the insoluble matter was dried under vacuum to obtain product 1. 4 g of ammonium fluoride pellets were dissolved in deionized water, and product 1 was added and mixed thoroughly. The mixture was stirred at 25°C for 6 hours. The mixture was washed three times with deionized water and then with anhydrous ethanol, then centrifuged at high speed and dried under vacuum at 60°C for 12 hours to obtain product 2.

[0044] (2) Product 2 was dissolved in 50 ml of anhydrous ethanol, and 6 g of tannic acid, an organic corrosion inhibitor, was added. The mixture was stirred at a constant temperature for 30 min and then vacuum-adsorbed for 2 h. During the vacuum-adsorption process, the vacuum degree must reach -0.1 MPa (gauge pressure) and must be maintained at this level during the vacuum-adsorption stage. The "constant temperature stirring-vacuum-adsorption" step was repeated three times. The product was washed with ethanol three times and dried to obtain a modified attapulgite loaded with tannic acid, i.e., Product 3, which is also the hybrid anti-rust pigment of the present invention.

[0045] (3) The formula of the hybrid anti-rust pigment based on attapulgite modified in epoxy coating is as follows: Component A: 60 parts of bisphenol A epoxy resin (NPSN-901-75X), 8 parts of hybrid anti-rust pigment, 0.4 parts of dispersant (BYK 110), 0.6 parts of wetting agent (BYK 306), and 0.6 parts of defoaming agent (BYK 065). -1 The mixture was dispersed at a high speed of 30 min, and then ground using a ball mill at a speed of 300 rpm for 6 h; component B: 36 parts of 650# polyamide curing agent and 30 parts of solvent xylene.

[0046] Components A and B were mixed to produce an anticorrosive coating containing an antirust pigment based on an inorganic acid, ammonium fluoride, and organic acid-modified attapulgite. The coating was sprayed onto sandblasted Q235 carbon steel (150 mm × 70 mm × 2 mm for salt spray testing and 50 mm × 50 mm × 2 mm for electrochemical impedance spectroscopy testing) and cured at room temperature for 72 hours. The dry film thickness of the coating was 67 ± 3 μm.

[0047] The results of the salt spray test of the embodiment and the comparative example are shown in Table 1: Table 1 360 h salt spray test results As shown in Table 1, the results of the examples and comparative examples illustrate that after the hybrid anti-rust pigment of attapulgite modified with an organic acid corrosion inhibitor was added to the epoxy varnish on the carbon steel surface, after 360 hours of salt spray test, the rust width was reduced compared with the rust width of the epoxy varnish coating with attapulgite added and attapulgite modified with ammonium salt, indicating that the organic acid corrosion inhibitor slowed down the corrosion rate of carbon steel and delayed the corrosion of carbon steel, proving the feasibility of this hybrid anti-rust pigment in application.

[0048] The present invention makes full use of the pore structure of attapulgite, and increases the pore structure of attapulgite through inorganic acid purification and inorganic salt modification. Finally, the organic acid corrosion inhibitor is "pressed" into the pore structure of attapulgite by pressurization, thereby realizing the combination of "attapulgite-organic acid". On the one hand, the impurities and a large amount of bound water in the attapulgite are removed by inorganic acid purification. On the other hand, the pore structure of the attapulgite is increased by inorganic salt modification to load more organic acid corrosion inhibitor. The former can remove impurities and expose the pore structure of the attapulgite itself, while the latter can increase the pore structure of the attapulgite to load more organic acid corrosion inhibitor, ultimately allowing this hybrid anti-rust pigment to exert its corrosion inhibition ability in the coating.

[0049] Other embodiments of the present invention will readily occur to those skilled in the art after considering the specification and practicing the embodiments disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the claims.

Claims

1. A hybrid anti-rust pigment based on attapulgite modification, characterized in that: The pigment is attapulgite modified by chemical inorganic acid activation treatment, and comprises 5-15 parts of attapulgite, 300-700 parts of inorganic acid, 2-4 parts of inorganic salt and 4-6 parts of organic acid corrosion inhibitor in parts by weight.

2. A method for preparing a hybrid anti-rust pigment based on attapulgite modification according to claim 1, characterized in that: The steps include: (1) Activating attapulgite with an inorganic acid to prepare an attapulgite suspension, and centrifuging the suspension to remove the insoluble matter to obtain product 1; (2) dissolving the inorganic salt in deionized water, mixing with the product 1, centrifuging to obtain the insoluble matter and vacuum drying to obtain the product 2; (3) The organic acid corrosion inhibitor was dissolved in anhydrous ethanol and then mixed with the second product. The mixture was stirred at a constant temperature for 30 min and then vacuum adsorbed for 2 h. The constant temperature stirring and vacuum adsorption steps were repeated 3 times. The organic acid corrosion inhibitor was loaded into the pore structure of the attapulgite by pressurization, washed with ethanol, and vacuum dried to obtain a hybrid anti-rust pigment.

3. The method for preparing the hybrid anti-rust pigment based on attapulgite modification according to claim 2, characterized in that: The raw material used in the chemical inorganic acid activation method is one of sulfuric acid, hydrochloric acid and nitric acid; the inorganic salt is one of ammonium fluoride and ammonium chloride; and the organic acid corrosion inhibitor is one of tannic acid, gallic acid and phytic acid.

4. The method for preparing the hybrid anti-rust pigment based on attapulgite modification according to claim 2, characterized in that: In step (1), the mass ratio of attapulgite to inorganic acid is 5-15:300-700. After ultrasonic dispersion for 30 min, the attapulgite suspension is prepared by high-speed stirring at a constant temperature of 70°C for 6 h.

5. The method for preparing the hybrid anti-rust pigment based on attapulgite modification according to claim 2, characterized in that: In step (2), the mass ratio of inorganic salt to deionized water is 2~4:340~670, the temperature of constant temperature stirring and dispersion is 15~25℃, and the time is 4~8 hours.

6. The method for preparing the hybrid anti-rust pigment based on attapulgite modification according to claim 2, characterized in that: In step (3), the mass ratio of the organic acid corrosion inhibitor to anhydrous ethanol is 4-6:50-100, the constant temperature stirring temperature is 20-25°C, the vacuum drying temperature is 50-70°C, and the drying time is 10-14 h.

7. A use of the hybrid anti-rust pigment based on attapulgite modification according to claim 1 in an anti-corrosion coating, characterized in that: The anti-corrosion coating includes component A and component B. Component A is prepared by the following components and mass ratios in parts by weight: 40-60 parts of solvent-based bisphenol A epoxy resin, 20-30 parts of solvent xylene, 0.4-0.6 parts of dispersant, 0.4-0.6 parts of wetting agent, 0.6-1.0 parts of defoaming agent, and 1-10 parts of hybrid anti-rust pigment; component B includes 20-40 parts of 650# polyamide curing agent.

8. The use of the hybrid anti-rust pigment based on attapulgite modification in anti-corrosion coatings according to claim 7, characterized in that: 1 wt.%~10 wt.% of chemically acid-activated and loaded-modified attapulgite was added to component A of the anti-corrosion coating, dispersed in a high-speed disperser for 30 min, and ground in a ball mill for 4~12 h to obtain component A of the anti-corrosion coating containing a hybrid anti-rust pigment based on chemically acid-activated and loaded-modified attapulgite. Components A and B were mixed and applied on the surface of carbon steel to form an anti-corrosion coating.

Images